The present invention relates generally to shelf-type storage rack systems. More particularly, the present invention relates to the support framing system and an improved cross bar attachment used to create the framing for storage shelves. The cross bars of the present invention are locked or secured against undesired movement and rolling to create a shelf that properly supports loads. Further, the locking cross bars are also readily removable and reusable.
Shelf-type storage racks are widely known in the art. Various racking systems can be seen throughout the residential storage, retail sales and warehouse industry. Typical shelf-type storage racks include at least four vertical columns rigidly interconnected by generally horizontal deck beams which are positioned in a transverse relation between opposing pairs of columns. These columns are then spaced apart in a parallel relationship by cross bars and often diagonal members. Shelves are then supported upon the horizontal deck beams and the cross bars. As is typical in known, shelf-type systems, a series of wooden slats or plywood decking is placed between the opposing deck beams to form shelves where pallets and other loads may be stored and accessed by warehouse personnel. The front of the shelf is usually adjacent to an access aisle, where warehouse personnel typically use high lifts, fork lifts and the like to place and remove pallets and their loads from the shelves.
As indicated above, one common way of creating the storage shelves is the use of wooden slats, typically two-by-fours, that extend between the deck beams. When using this method, the front and back deck beams are typically roll formed prior to installation to provide a ridge or lip on their upper surface upon which the wooden slats are placed. However, in this configuration, the slats are prone to being knocked-out, skewed or otherwise misaligned between the deck beams. If this shifting or knock-out of one or more slats is unknown to the warehouse personnel, subsequent placement of a load could result in the load falling, leading to injury to the personnel and/or damages to the load, equipment or rack structure. At best, making sure that the slats are properly positioned between the deck beams is time consuming for the warehouse personnel. In another method of creating storage shelves, wooden slats are inserted in the channels between the opposing deck beams. Although an improvement, this method has disadvantages such as increased construction costs and decreased flexibility.
In the past, it has been found that where a decking panel structure has been installed in a shelving rack structure, there is some tendency for the deck beams and cross bars supporting the shelving rack structure to bow in such a way that the structural members tend to roll and/or move apart. Where the load is heavy enough, the decking panel structure comprising the wood or steel decking, as a result of the movement of the structural members, tends to drop off of the beams. In order to overcome such movement, often rack frames must be welded or attached together by bolts, for simple assembly and disassembly. While welded racks may be strong, they cannot be easily disassembled for moving and the labor involved in welding them together is substantial. Bolted racks, while easily assembled, exhibit the additional problem that any looseness in the beam to column connection will result in a leaning, wobbling rack. This in turn induces higher stresses in many of the components which might cause collapse of a heavily loaded rack.
Also, problems may arise because of irregularities in the floor of the warehouse or other place where the rack is positioned. This, along with small errors in the length and width of the beams and columns as well as the positioning of bolt holes therein, can result in the creation of unpredictable positional variations in the beams and columns as one attempts to affix them together. This, in turn, may create significant difficulties in getting a tightly bolted connection between the beams and columns, since the parts may not quite fit precisely together because of the unpredictable positional variations.
There is therefore a need for an improved system for attaching the structural members of a shelving rack support frame. There is a further need of an improved cross bar attachment used to create the framing for storage shelves. Still further there is a need for cross bars that are readily removable and reusable yet can be locked or secured against undesired movement and rolling to create a shelf that properly supports loads.